Light source devices play an important role in human life, and may be applied in various areas such as in a building, in a vehicle, or on a decoration article. Light source device is not only an illumination tool but has great impact human daily life.
General light source devices include an incandescent lamp, a fluorescent lamp, and a light emitting diode (LED) lamp, etc. In a conventional incandescent lamp, electricity is conducted through tungsten filaments to generate light by high heat for illumination. However, such an incandescent lamp consumes a lot of power, and hence being gradually substituted by fluorescent lamps.
A fluorescent lamp generally applies high voltage on electrodes to emit electrons hitting mercury vapor atoms for generating ionization and excitation phenomena. When the mercury vapor atoms return to an original state from an excitation state, an invisible electromagnetic wave of 253.7 nm in wavelength is emitted. Thereafter various fluorescent materials can be used to absorb and convert the electromagnetic wave into visible lights, such that the fluorescent lamp may emit various colors of light in accordance with the fluorescent materials.
Although the lighting efficiency of the fluorescent lamp is better than that of the incandescent lamp, yet in the society advocating energy saving and environmental protection, people still continue to develop new lighting devices which can meet requirements of energy saving and environmental protection for substituting the fluorescent lamp, because of the mercury vapor contained the fluorescent lamp. Therefore, a light-emitting diode (LED) lighting module is developed and greatly expected. When a LED is under a proper forward bias voltage, electrons and electron holes are respectively injected to N and P terminals. Then, the electrons and electron holes are combined at a P/N junction, thereby enabling the LED to emit light caused by the energy released in the form of light when the electrons drop to a basic state from an excited state to combine with the electron holes.
The lighting efficiency of the LED is better than that of the fluorescent lamp, and hence the LED has better energy saving performance than the fluorescent lamp. However, the light source device using the LED has poor light uniformity since the LED has a high directivity.
Therefore, there is a need to develop a novel light guide element and a light source device using the light guide element for providing uniform light.